Our current emphasis is on Radical Alkylation Carcinogenesis by Carbon Tetrachloride and the like. Our questions are: (a) What are the covalent reactions and reactivity of the products between base residues and the ultimate radical carcinogens .CC13 and .CH3? (b) How are the radicals bound to DNA and what are the subsequent physicochemical changes? (c) Will the DNA attached CC13 groups react with the various types of chromatic nucleophiles to modify the alkylated DNA further? The approach: Attempt reactions of .CC13 and .CH3 with nucleosides A, C, G, T. U, and follow rates. Use 14C or 13C labeled CC14 etc. to react with DNA in the presence of microsomes or a chemical initiator. The level of alkylation and its physicochemical changes as well as covalent products will be determined.